Placing ladders on an uneven ground surface creates significant risks of injury to the user, whilst standing on the ladder and ascending and descending. Many injuries have been sustained as a result of falls from unstable ladders. Sloping ground, inclined surfaces, rocks and steps all contribute to the problem. It is particularly prevalent on building sites, where uneven ground and building rubble constitute the majority of the ground surface.
Uneven ground surfaces also present a problem when trying to position other items such as water storage tanks and seating, such as park benches. The uneven ground surface can result in the need for clearing of the ground before positioning the structure, or the structure is positioned unlevelled.
There have been a number of attempts to provide a levelling device for ladders. Some of these include a support arc that is connected to the bottom of the ladder via locking devices. The support arc is moveable through the locking devices to position its two feet on the ground surface, whilst allowing the ladder to remain substantially upright. However, many of these devices have a tolerance fit between the support arc and the locking device, which requires the user to manually slide the support arc through the locking device to adjust the level of the ladder. This can prove difficult when the ladder is relatively tall and heavy and in effect the ladder must be completely lifted off the ground to remove the weight to allow the components to be manually slid.
Attempts to remove manual adjustment use a spring system to urge the locking device into an unlocked position in which the support arc is free to pass through the aperture in the locking device. When weight is placed on the ladder the locking device moves into a locked position. There are a number of problems associated with these devices, as the springs lose their tension after repeated use such that the locking device does not return to the unlocked position. The support arc can become stuck in the aperture and the locking device jams in a locked position.
It is therefore an object of the present invention to provide an improved adjustable support device for attachment to a structure that at least in part alleviates some of the known problems with existing systems, or at least to provide the public with a useful choice.
Any reference in this specification to the prior art does not constitute an admission that such prior art was well know, forms part of the common general knowledge, or would be found by a person working in the field of the invention.